If you’re a healthy person trying to get fitter, or indeed an unhealthy person looking to get healthy – and you’re serious about it, I have one piece of advice for you.

Being in good shape is of course a complex blend of lifestyle, genetics, circumstances and so on. This is not the advice part by the way. Some of these things are beyond our control, but we can to a large extent get or stay in shape by managing our diet and exercise.

It seems to be that you need to do both. We’re subject to a basic calculation: calories in and calories out. In that sense we’re a bit like cars, taking in fuel and using it up to do work. The more we exercise, the more we can eat, put in an over-simplified way. If you burn less calories than you absorb, you gain weight. If you burn more, you lose weight. You could do 100’s of sit-ups a week, but if you can’t cut out the rubbish, you won’t see the benefit.

Now I’m partial to rubbish. Very partial. Cakes, sweets, biscuits, chocolates – these are the 4 basis food groups as far as I’m concerned. Added to that, I’m not as sprightly as I used to be, and nor’s my metabolism. So this is only going to end one way if I’m not more careful.

Here’s where I get to my advice, which if course I already gave you in the heading. Keep a food diary. I have kept one for the last 5 years, recording in general terms what I’ve been eating. It’s not particularly scientific, but what I do find is that it helps me acknowledge exactly what I’m eating, and that for me is half the battle. If you ate 4 chocolate biscuits after your tofu salad, then record them. I also try to record how much water I drink (I can’t stand water; it’s an effort for me to drink it) as well as tea and coffee. Finally, I also record any exercise I do that’s more strenuous than a walk around the block. Any day without any exercise is recorded as ‘Black Day’.

Recording exactly what you eat reminds you of exactly what you eat. When you’re monitoring it, you’re effectively measuring it. And as the business gurus will tell you, if you can measure it, you can manage it.